Fig. 3.

Comparison of APT 3D reconstructions of bacterial magnetite (tip 514) (Top) and control samples (Bottom) for IM-SDS (Left; tip 3480), BMNPs (Middle; tip 3468), and L-MNPs (Right; tip 3733) (see also SI Appendix, Tables S1, S2, and S4). For the BM, note the presence of C and N (occupying spaces inside C layers), reconstructed as isosurfaces at the same atomic % as that measured for these elements in these specific tips (see SI Appendix, Table S1), inside magnetite (represented by the FeO distribution). For the control samples, C resulting from contamination (red arrows) is not inside the magnetite but is rather found on the outside of the tips.